Typically, a display device (graphical user interface) having a CT software function is employed in an industrial X-ray CT device. Note that an X-ray radioscopic imaging device performs X-ray photography by obtaining a single piece of projection data, or by irradiating X-rays, sequentially obtaining a plurality of pieces of projection data, and displaying each of the projection data in real time (video display). Thus, by performing X-ray radioscopy, it is possible to check whether or not the projection data presents an optimum image by monitoring the image in the middle of the X-ray radioscopy. Therefore, even when an imaging condition is not suitable, the imaging condition can be changed in the middle of the X-ray radioscopy on the basis of the monitoring result.
In this regard, the X-ray CT device obtains a reconstructed image (CT image) by performing a reconstruction process using a plurality of pieces of projection data (for example, approximately 600 to 2,400 pieces of data). Therefore, unlike the X-ray radioscopic imaging device, when CT imaging is performed by the X-ray CT device, it is not possible to check whether or not the reconstructed image is optimum until the CT imaging and the reconstruction process are terminated. Therefore, when the CT imaging condition is not suitable, it is necessary to restart the CT imaging and the reconstruction process from the beginning. Even when the CT imaging is restarted, a user is not allowed to know whether or not the reset (changed) CT imaging condition is optimum before checking the reconstructed image obtained from the restarted imaging. In some cases, it is necessary to repeat the CT imaging over and over until an optimum reconstructed image is obtained.
In this regard, it is necessary to set an optimum CT imaging condition in advance before CT imaging. In the field of the X-ray CT device of the related art, a technique of setting an optimum CT imaging condition has been proposed (for example, see Patent Documents 1 and 2). Typically, when a user determines that the set CT imaging condition is optimum, the user performs an input operation for confirming the CT imaging condition by clicking an imaging condition input confirmation button displayed on a display screen of the graphical user interface (GUI). Then, the CT imaging is performed on the basis of the confirmed CT imaging condition.
In the field of the industrial X-ray CT device, the CT imaging is performed for various materials and structures with various image resolution requirements (such as a spatial resolution or a density resolution) and various imaging times. Therefore, since a wide variety of imaging conditions are set freely, the imaging conditions are to be set for each target object (work) as described below.                X-ray Condition: the X-ray condition includes a tube current or a tube voltage of an X-ray tube that generates X-rays.        Exposure Time: the exposure time is a net X-ray irradiation time.        Number of Views        Average Number: the number of views and the average number described above have the following relationship. Specifically, the “number of views” refers to an average number of scanned images for the same projection angle or for each projection angle including the vicinity of a target projection angle (that is, projection angles in the vicinity of the imaging time at the target projection angle), so that the number of scanned images required in the CT imaging becomes “number of views×average number”. For example, when the number of views is set to “600” and the average number is set to “3”, the number of scanned images necessary in the CT imaging becomes “1,800 (=600×3)”. Note that, when the projection data are averaged at each projection angle including the vicinity of the target projection angle, the projection data at each projection angle are approximated to the projection data at the same angle as that of the target projection angle.        Slice Thickness        BH Correction Data Selection: the BH correction refers to “beam hardening correction”. Note that the beam hardening correction herein refers to correction using image processing software (image processing algorithm).        Scaling Factor: the scaling factor herein refers to a response characteristic used in grayscale correction (also called “gamma correction”).        
In addition, the imaging condition includes a distance from a focal position to an X-ray detector (source-to-detector distance: SDD) in a vertical direction when the vertical line is drawn from the focal position of the X-ray tube to the X-ray detector, a distance from the focal position of the X-ray tube to a rotation center of the target object (source-to-rotation-center distance: SRD), a CT imaging mode (such as cone beam CT (CBCT)), a scan count, a total scan time, and the like.
Patent Document 1: JP-A-2009-112627
Patent Document 2: JP-A-2011-080971